WTA Stuttgart - Maria Sharapova vs. Ana Ivanovic (14:00 BST)

Maria Sharapova takes on Ana Ivanovic this afternoon in the quarter-finals of the 2013 Porsche Tennis Grand Prix in Stuttgart (14:00 BST start).

Sharapova will have to step up a gear after an unconvincing display against Lucie Safarova in the second round of this week's WTA Stuttgart, eventually coming through 6-4 6-7 6-3.

"I knew today was going to be difficult - I was playing a good opponent with tremendous results on clay, and in general she's not an easy opponent to play against," Sharapova told reporters afterwards.

"I needed to be ready. And there were some things I was disappointed with - I don't think I took advantage of some of the shorter serves she hit, especially on her second serve - that's something I'll definitely be working on. But no matter how long it took today, I'm happy I got myself through this match."

She added: "I feel like I had the momentum going into the tie-break in the second set - I wasn't able to close it out, but when it comes to a third set you just have to start from scratch again. I thought about what was working well for me before the tie-break and in the first set too, and tried to do those things again. It was a good effort."

Ivanovic has been on fire over the past week and she continued her form with a 6-4 6-3 win over eighth seed Nadia Petrova in round two, hitting back from a break down in both sets.

Sharapova has won five of her seven matches against Ivanovic, including a win in the 2008 Australian Open final. Ivanovic beat her 6-2 6-1 in the French Open semis back in 2007. However, Sharapova won both their matches in 2012, including a 7-6 6-3 win on the clay of Rome.